In a starter disclosed in JP-U-1-166275, a cylindrical tube is slidablly engaged with an outer peripheral surface of an output shaft through a bearing. An end of the tube is closed with a plate. A straight ventilation groove is formed on the inner cylindrical surface of the tube in an axial direction to communicate an enclosed space defined around an end of the output shaft in the closed end of the tube and a space defined rearward of the bearing (a space in a one-way clutch).
Since the ventilation groove is formed into a straight line in the axial direction, when the bearing is press-fitted in the tube, the bearing is likely to be partially deformed and projected into the ventilation groove. Specially, in a case that an inexpensive wrapping bearing that is formed by rounding a rectangular-shaped plate into a cylindrical shape is used as the bearing, if a joint portion of the cylinder is moved along the ventilation groove while the bearing is press-fitted in the tube, the bearing is deformed and largely protruded into the ventilation groove.
In this state, even when the inner surface of the bearing is drawn to improve a precision of an inner diameter of the bearing, it is difficult to properly draw the portion of the bearing that is deformed or projected in a radial direction of the bearing. Therefore, a performance of the bearing is likely to be lessened. Further, it is likely to cause a starter performance deterioration.
Further, when the bearing press-fitted in the tube is partially protruded into the ventilation groove, a space of the ventilation groove is decreased. As a result, a flow of air in the ventilation groove is likely to be worsened.